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<br />Colony's development project for 1987 involves excavation of a channel <br />through the stockpile in Upper Davis Gulch, and using the material produced <br />in this excavation to make some grading improvements at the mouth of the <br />valley at the western end of the Dam Access Road. These improvements will <br />flatten an existing steep grade on the Plant Access Road, establish a channel <br />in the Dam Access Road valley, and complete all earthwork necessary for <br />permanent reclamation of the area. Upon completion of the earthwork, <br />scheduled for late summer, the area will be reseeded with a permanent seed <br />mix. Finally, if materials are produced in excavating the channel in excess <br />of the amount needed to complete the grading work described above, these <br />excess materials will be hauled up to the Switchyard Fill (one half mile <br />southeast of the Plant Site) and used to further the construction of that <br />• fill. Exxon's earthwork balance calculations indicate that some filling at <br />the Switchard Fill will probably be required, depending on the swell factor <br />for the material excavated to form the drainage channel in Upper Davis Gulch. <br />Because the anticipated service life of the channel is uncertain, it has <br />been designed to standards appropriate for long term service. The channel <br />will handle flows up to a 100 year flood (3421 cfs)1. The channel lining to <br />1) Source of flow estimates is the 1981 Final Design Report for Davis <br />Gulch Dam prepared by PRC Consultants, Inc., Table A - 9. <br />• <br />